基于甲烷化反應的催化劑顆粒設計與過程強化

李軍，朱慶山，李洪鐘

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基于甲烷化反應的催化劑顆粒設計與過程強化

李軍，朱慶山，李洪鐘

（中國科學院過程工程研究所多相復雜系統國家重點實驗室，北京100190）

甲烷化反應過程的主要問題是“燒結”和“積炭”。基于甲烷化反應的強放熱、減分子特性和對反應機理的認識，從催化劑與反應器的匹配性角度，論述了當前的主要甲烷化工藝、甲烷化催化劑、甲烷化反應及過程強化方法。流化床技術可有效防止催化劑的積炭和燒結，從與流化床反應器匹配的催化劑結構設計源頭出發，制備具有耐磨損、易流化、低密度的高活性甲烷化催化劑，是流化床甲烷化發展的一個重要途徑。

甲烷化；流化床反應器；強放熱；減分子；鎳催化劑；積炭

引 言

我國“富煤、貧油、少氣”的能源結構特點決定了煤炭在能源利用中占主導地位，并且在今后相當長的時期內不會改變。然而，持續增加的天然氣需求及日益嚴格的環保要求促使人們尋求新的煤炭利用途徑和天然氣來源。這使得煤制天然氣技術的迅速發展成為煤炭潔凈利用的選擇之一。

煤制天然氣是煤經過煤氣化、合成氣變換、凈化、甲烷化等化學反應最終獲得清潔燃料甲烷的過程[1]。其中，煤氣化和合成氣甲烷化是煤制天然氣技術體系的核心。到目前為止，作為煤炭三大利用途徑之一的煤氣化技術已經成熟。然而，甲烷化技術僅有國外少數幾個公司掌握，尚未實現國產化。甲烷化技術的核心是甲烷化催化劑和甲烷化反應器的研制和開發，其關鍵在于如何有效控制催化劑床層溫度，避免因反應的強放熱導致床層局部飛溫現象[2-3]。

本文系統地論述了當前主要的甲烷化工藝、甲烷化催化劑和甲烷化反應機理的主要進展，提出了基于甲烷化反應機理的流化床反應器和催化劑顆粒設計是未來流化床甲烷化工藝的發展方向，以期為甲烷化工藝的進一步應用開發提供指導。

1 甲烷化工藝研究現狀

甲烷化反應的一個重要工業應用是合成氨、燃料電池等富氫氣體中痕量CO的脫除[4-9]，但更加引人關注的應用是煤/生物質氣化甲烷化制天然氣工藝[10-17]。煤制天然氣工藝大致包括煤氣化、合成氣變換、凈化和甲烷化等，如圖1所示。首先煤氣化使煤顆粒與水蒸氣和氧氣在高溫下反應得到粗合成氣，主要成分包括H2、CO、CO2、H2O、CH4和少量碳氫化合物，含S、Cl雜質，其組分含量與氣化工藝條件、反應器類型、氣化劑等密切相關；由于粗合成氣中焦油、含S/Cl等微量雜質氣體對后續的反應器甲烷化催化劑有損害，需要經過氣體凈化裝置處理；凈化處理后的氣體經水煤氣變換反應調整H2和CO比例為3左右；進入甲烷化反應裝置和提純裝置得到甲烷（>95%）。

表1概括了甲烷化過程主要反應，反應（1）為甲烷化反應的主反應，但實際反應過程中，存在CO歧化（2）、甲烷分解（3）等副反應，使催化劑表面積炭，降低催化劑的活性和使用壽命。同時甲烷也可能通過CO2甲烷化反應（4）和逆CO2-CH4重整反應（5）獲得。其中反應（5）可以認為是甲烷化反應和水蒸氣變換反應（6）的疊加。從熱力學上分析，甲烷化反應為減分子的強放熱反應，增加壓力和低溫對甲烷化反應有利。但在動力學上高溫有利于提高甲烷化反應速率，同時從能量利用角度考慮，高溫甲烷化有利于提高能量利用率，近年來受到研究者們的高度關注[18-19]。然而，在高溫條件下催化劑積炭和活性金屬燒結等問題是嚴重影響高溫甲烷化的不利因素。因此，甲烷化工藝的難點在于如何有效控制反應區域的溫度，防止催化劑積炭、燒結失活。其關鍵是甲烷化反應器和甲烷化催化劑的開發。

表1 甲烷化工藝過程主要反應和副反應[20-21]

1.1 固定床甲烷化工藝

甲烷化反應器與甲烷化催化劑并列為甲烷化技術的兩大核心[22]。自20世紀50年代，研究者就開始致力于甲烷化反應器的開發，如固定床、流化床和漿態床甲烷化反應器[23-25]。由于固定床具有反應速率高、催化劑用量少、催化劑不易磨損等優點，已經成熟的工業化甲烷化技術普遍采用絕熱多段固定床甲烷化反應器，包括丹麥托普索公司（Topsoe）的TREMPTM技術[26]、英國戴維公司（Davy）的CRG技術[27]和德國魯奇公司（Lurgi）的甲烷化技術[28]，均采用了固定床甲烷化反應器。但由于固定床反應器傳熱性能差，如何移出甲烷化反應大量放熱是固定床甲烷化技術的關鍵。通常采用多段絕熱式固定床反應器的串聯方式，通過控制各段反應器的轉化率、部分產品氣體循環和內置或外置預熱器等方法實現反應過程的溫度控制。根據催化劑的耐受溫度范圍不同，其甲烷化工藝的操作溫度和回收熱量的方式有所不同。比如，丹麥的TREMPTM技術的特點是采用MCR-2X催化劑具有寬的溫度窗口（250～700℃），在較高溫度下（600℃）運行，可減少氣體循環量和回收高壓蒸汽熱量，能量利用率高[29]。Davy的CRG甲烷化技術的特點是采用CRG催化劑具有變換功能，不需要調節合成氣的H/C比，并且在250～700℃具有較高活性[30]。魯奇甲烷化工藝的特點是甲烷化反應溫度較低（450℃），采用氣體循環限制原料氣的進口溫度（<300℃），防止催化劑積炭[31]。最近報道顯示，魯奇甲烷化工藝為了提高競爭力，開發了高溫甲烷化催化劑，提高了甲烷化反應溫度[32]。3種甲烷化技術各有特色，魯奇和戴維的甲烷化技術得到了美國大平原項目的長期驗證[33-34]，引進托普索甲烷化技術的新疆慶華年產55億立方米煤制天然氣項目一期已于2013年8月竣工投產，產出的煤制天然氣已送入西氣東輸管線[35]。而采用戴維甲烷化工藝的大唐內蒙古克什克騰旗年產40億立方米煤制天然氣一期示范項目已于2013 年12月投運，正式向北京供氣[36]。

甲烷化反應器的設計通常與甲烷化工藝和催化劑配套，其反應器結構中很多經驗取值與其配套工藝和催化劑密切相關，是甲烷化技術的關鍵技術之一。由于甲烷化反應具有反應迅速、放熱量大、易積炭等特點，在反應器設計中，除了防止催化劑床層飛溫、積炭失活問題外，還需要考慮諸如床層熱點穿出、水浸入催化劑結構性破壞和反應器冷熱位移等問題[37]。由于甲烷化工藝與催化劑高度匹配，目前只有丹麥托普索公司、英國戴維公司和德國魯奇公司等少數公司掌握固定床甲烷化技術，國內鮮有關于固定床甲烷化反應器結構的文獻報道。

多級串聯的固定床反應器結構使得整體設備和流程相對復雜，工藝參數控制相對較難，同時需要返回大量的產品氣稀釋原料氣，限制了生產能力，并且增加了動力消耗，因而操作成本較高，影響了工藝的整體經濟性。為克服工業固定床工藝中的缺點，許多研究機構對甲烷化工藝及其設備進行改進，開發了流化床工藝和漿態床工藝。

1.2 流化床甲烷化工藝

與固定床反應器比較，流化床反應器具有相間接觸良好、床層溫度均勻的特點，易于規模化連續化操作的優勢，特別適合于應用于強放熱的甲烷化反應。1950～1980年間，先后有多個國家參與開發流化床甲烷化工藝，主要有美國礦務局（Bureau of Mines）建立的多段流化床甲烷化工藝[38]、美國Bituminous Coal Research Inc. (BCR, United States)公司的Bi-Gas流化床甲烷化工藝[39]和德國卡爾斯魯厄大學（University of Karlsruhe）與Thyssenga公司合作開發的Comflux甲烷化工藝[40]。其工藝參數和運行狀況列于表2中[38-42]。

表2 典型的流化床甲烷化工藝參數

從表2中看出，美國礦務局（Bureau of Mines）建立的煤氣化甲烷化制天然氣流化床工藝的規模較小，其流化床直徑僅為1.9～2.54 cm。催化劑采用Fe基或Ni基催化劑（p=63～180mm），運行結果顯示鎳基催化劑優于Fe基催化劑，床層溫度控制較好，CO和H2轉化率95%～98%，但該工藝自1956年后未見有報道[38]。

Bi-Gas工藝流化床反應器直徑15 cm，反應區高度2.5 m。催化劑采用NiCoMo/Al2O3催化劑，具有水煤氣變換和甲烷化功能[41]。但運行結果顯示，在催化劑量23～27 kg，H2/CO比1.4～3，表觀氣速2.4～5.5 cm·s-1（8～18倍mf）條件下，CO和H2轉化率70%～95%，還需要進一步提高轉化率。但在運行過程中發現，在甲烷化反應初期催化劑顆粒的磨損較為嚴重。自1979年Cobb等[39]利用其運行數據計算了CO反應動力學和建立了兩相流數學模型之后，未見與Bi-Gas甲烷化工藝及流化床反應器的文獻報道。

Comflux工藝的突出特點是水煤氣變換反應和甲烷化反應集中在一個流化床中進行。與前兩個流化床甲烷化工藝比較，Comflux工藝規模顯著提高，流化床反應器直徑為40～100 cm，能容納1000～3000 kg催化劑(p=10～400mm)，SNG 生產規模達到2000 m3·h-1。考慮到省去了變換單元和產品循環氣壓縮機，該工藝降低了投資運行的成本，比固定床工藝減少了將近10%的成本。該工藝通過了中試和半商業運營，尚無商業化規模的運營。受石油價格影響，該裝置自20世紀80年代中期終止運行。

除了以上3種煤基甲烷化流化床工藝外，自20世紀90年代，瑞士PSI (Paul-Scherrer Institut, Switzerland)公司開始致力于生物質轉化制SNG技術開發，稱為PSI流化床甲烷化工藝[43-46]。其核心技術源于Comflux流化床甲烷化技術，催化劑同時具有水煤氣變換反應和甲烷化反應的功能。該工藝于2007年在10 kW SNG中試規模的裝置上運行了1000 h，結果顯示產品氣含有高達40%的CH4和極少量的CO，并于2009年在1 MW SNG PDU規模裝置上完成驗證。2010年初，PSI工藝與奧地利的快速內循環流化床氣化工藝（FICFB gasifier）嫁接形成具有競爭力的甲烷化技術，預計2016年建成100 MW SNG的甲烷化工藝。

1.3 漿態床甲烷化工藝

漿態床反應器以液態惰性烴為反應介質，涉及氣、液、固三相反應器，由于其反應系統的熱穩定性高，系統溫度可以達到瞬間平衡的特點，非常適用于甲烷化反應。其基本工藝原理是反應器下部通入原料氣和流化用液體，與流化床中懸浮的Ni 催化劑作用進行甲烷化反應。反應熱被液體吸收。由于液體熱容量大，反應基本是在等溫條件下進行。氣化的流化液體與產品氣體在反應器外部用熱交換器進行冷卻分離，液體進行循環再利用。美國化學系統研究所(Chem. System)開發了LPM（liquid phase methanation）工藝，該工藝在bench-scale unit (BSU)、process development unit（PDU）、pilot plant（PP）3種規模的實驗裝置進行了驗證，其工藝條件和裝置規模見表3[46-48]。在PP裝置上運行300 h結果顯示，該工藝存在甲烷合成效率較低、催化劑損失嚴重的問題，于1981年被終止。

國內太原理工大學、中國礦業大學（北京）等科研機構也對漿態床甲烷化進行了研究[49-51]。太原理工大學的研究表明，漿態床CO甲烷化在280℃的反應溫度下，CO的轉化率保持在96%以上，取得了很好的反應結果[49-50]。目前，該工藝還在研究開發階段，未見到工業化項目相關報道。

表3 漿態床甲烷化工藝參數

1.4 甲烷化反應器性能對比分析

從以上甲烷化工藝及甲烷化反應器的研究結果可以看出，甲烷化反應器的設計是整個甲烷化工藝的關鍵技術。一個理想的甲烷化反應器應具有高效的傳熱性能、防止催化劑積炭失活和減少催化劑損失等優點。

表4列出了固定床、流化床和漿態床甲烷化工藝的性能，可以看出，漿態床反應器的CO轉化率低、催化劑磨損嚴重，仍然處于實驗室研究階段，距離工業化較遠。固定床具有CO轉化率高、催化劑用量少、催化劑無磨損等優點。但固定床工藝流程和結構復雜，運行成本高。流化床甲烷化工藝CO轉化率高，具有流程結構簡單、生產能力大等優勢，操作成本較固定床低，但存在催化劑磨損嚴重問題，制約了其工業化進展。因此，未來流化床甲烷化工藝的研發重點在于如何防止催化劑磨損和研制抗磨損的甲烷化催化劑。

表4 固定床、流化床和漿態床甲烷化工藝對比[35,46]

2 甲烷化催化劑研究現狀

自1902年Sabatier等[52]發現在Ni及其他金屬(Ru、Rh、Pt、Fe、Co)催化劑能催化CO甲烷化反應以來，甲烷化催化劑的研究一直是該技術關注的焦點，涉及了甲烷化反應熱力學、反應動力學、催化反應機理、失活機理等多個方面[53-60]。大量的研究表明第Ⅷ族金屬及Ag和Mo均有甲烷化活性，其單位金屬表面的甲烷化催化活性順序依次為Ru>Ir>Rh>Ni>Co>Os>Pt>Fe>Mo>Pd> Ag[20]。在眾多的金屬催化劑中，具有高甲烷化催化活性的有貴金屬Ru、Rh及過渡金屬元素Ni、Co、Fe、Mo等[61-66]。Fe、Co作為甲烷化催化劑的選擇性較差，且易積炭失活[67-68]。具有工業化應用前景的催化劑主要是Ru基和Ni基催化劑，Ru基催化劑比Ni基催化劑的催化活性高，為最理想的甲烷化催化劑，但因其價格昂貴，限制了它的工業使用[69-71]。鎳基催化劑由于其較好的甲烷化催化活性、選擇性高且價格相對低廉，是工業化甲烷化催化劑的主要選擇[72-76]。從目前已經工業化的甲烷化催化劑看，如托普索公司的MCR-2X[19,77]、戴維的CRG[78-79]以及魯奇公司的Cl-85[46,80]，均是鎳基催化劑，其典型的催化劑特點見表5。可以看出，高溫甲烷化技術和高溫甲烷化催化劑是未來甲烷化工藝的重點發展方向。

表5 商業化甲烷化催化劑的特點

到目前為止，國內研究機構開發的甲烷化催化劑主要是應用于中低溫微量CO脫除方面（部分甲烷化），而針對完全甲烷化的高溫甲烷化催化劑，由于沒有配套的甲烷化工藝的支撐，其甲烷化催化劑正處于研發階段，主要以實驗室研究為主，缺乏中試示范裝置和工業裝置驗證。國內中國科學技術大學研制的KD-306催化劑的CO轉化率僅40%～60%，甲烷選擇性>70%，上海煤氣公司研發的SG-100鎳基催化劑的CO轉化率為60%～74%，甲烷選擇性50%～63%[81]，遠低于工業化的甲烷化催化劑[82-83]。近年來，中科院過程所在催化劑載體、鎳粒子調控及甲烷化催化劑抗積炭方面進行詳細的研究，開發出多種活性高的Ni基催化劑[25,61,84-86]。北京低碳清潔能源研究所在耐硫型催化劑和寬溫型（250～700℃）Ni基甲烷化催化劑開發方面取得了進展，通過添加助劑MgO提高了NiO熱穩定性和甲烷選擇性[87-91]。但缺乏長時間的穩定性實驗驗證該催化劑的高溫穩定性。中科院大連化物所開發了高溫和低溫甲烷化催化劑，完成的5000 m3·d-1煤制天然氣甲烷化工業中試裝置已連續穩定運行超過1000 h[24]，為中國煤制天然氣技術的產業化發展向前邁出了關鍵一步。

在高溫甲烷化反應過程中，原料氣與甲烷化催化劑（鎳、助劑和載體組成）顆粒表面的Ni原子接觸并反應，其甲烷化催化劑活性決定于CO解離能和主要中間體在金屬催化劑表面的穩定性[58-60]，理想的催化劑是在兩個因素之間取得平衡。要求甲烷化催化劑具有高比表面積、高鎳分散性及與載體的強相互作用[92-94]。大量研究表明，導致甲烷化催化劑失活的原因有：(1)積炭[95-97]；(2)燒結[19,56,98-100]；(3)鎳流失[67,101]；(4)硫中毒[44,102-103]。針對硫中毒和鎳的流失，工業上一般采用對原料氣體進行深度預脫硫，高于生成Ni(CO)4溫度操作，使硫中毒和鎳流失問題得以解決。然而，高溫下積炭和鎳的燒結仍然是鎳基催化劑甲烷化工藝面臨的兩個技術難題。工業上，通常以犧牲生產能力和耗費能量來減少催化劑的積炭和燒結，如魯奇甲烷化工藝采用產品氣循環以稀釋原料氣控制反應器溫升，托普索公司就是采用從第二反應器出來的部分氣體循環到第一反應器入口來控制反應器溫度[31,104]。

催化劑積炭主要來源于CO的歧化反應和甲烷分解反應，積炭通常發生在催化劑床層上部和固定床反應器入口處[105]。生成的碳晶須或聚合炭會沉積在催化劑表面而覆蓋其金屬活性位，阻塞催化劑載體的孔道，使活性組分與載體分離，不僅造成催化劑的失活，縮短催化劑壽命[106-107]，還會增加催化床層阻力。Czekaj等[43]給出了積炭機理，該機理認為催化劑表面上的NiO 和Ni(OH)2不具催化活性，只有被H2還原后的金屬態Ni才具有甲烷化催化活性。催化劑活性降低的原因是金屬態Ni 晶格和-Al2O3晶格不匹配而形成了由Ni和NiC或Ni3C組成的一個薄層界面，造成活性組分鎳與載體間作用力弱，從而導致具有活性的Ni粒子從載體上脫落。另一方面，積炭會形成惰性炭層或低反應活性的碳化物覆蓋在催化劑表面，阻止反應進行。因此，選擇與鎳兼容性好的催化劑載體材料，以增強活性鎳與載體之間的作用力，是防止積炭的有效方法。

高溫或低溫高CO濃度甲烷化過程均會導致鎳催化劑燒結失活，鎳基催化劑的燒結失活存在兩種燒結機理[108]：一種是粒子遷移機理，即金屬晶粒在催化劑表面上遷移、碰撞、聚并長大；另一種是原子遷移機理，認為金屬原子從金屬晶粒上脫離開，在催化劑表面遷移，并被另一個晶粒捕獲。無論是哪一種燒結機理，都與催化劑載體結構、活性金屬含量、鎳與載體的相互作用密切相關[99-100]。由于甲烷化反應的強放熱特性，高溫下引起床層局部過熱是導致催化劑燒結失活的另一個主要原因。

由此可見，催化劑積炭和活性金屬燒結是甲烷化催化劑失活的兩個主要原因，并且受催化劑結構和操作條件影響較大。無論是積炭，還是鎳粒子燒結都與甲烷化的強放熱特性引起的床層過熱有關。一方面，從甲烷化催化劑本身出發，研制具有高熱穩定性的新型抗積炭抗燒結催化劑；另一方面從甲烷化工藝入手，比如產品氣循環以稀釋原料氣、通入水蒸氣以調節CO分壓等手段穩定床層溫度。另外，通過流化床反應器強化傳熱是甲烷化一個重要途徑。

3 甲烷化反應過程強化

關于CO甲烷化的動力學和反應機理的研究很多。早期的研究認為，氧中間體（CHO）是甲烷化反應的中間體[20]。但在甲烷化過程的紅外研究中沒有發現CHO物種的存在。Wise[109-111]提出了表面碳中間體機理并給出了甲烷化反應路徑，即CO 在催化劑表面解離得到表面碳原子（Cs），部分加氫（CH）后通過CO 的不斷插入和部分氫解作用使鏈增長，最終加氫使鏈終止。表面碳機理得到了大多數實驗的證實，但對氫氣在甲烷化中的作用和控速步驟目前尚未達成共識，最大分歧在于是CO直接解離還是氫助解離[112-114]，以及速控步驟是CO解離還是表面碳加氫[115-117]。甲烷化反應機理的爭論也反映了甲烷化反應的復雜性，但無論是何種加氫機理，CO在催化劑表面吸附都是關鍵。

大量研究表明，CO在催化劑表面解離生成的吸附碳是甲烷化反應的前驅體。催化劑表面的碳可以分為Cα、Cβ、石墨碳以及碳須[118]。其中，Cα是原子狀態的碳，低溫下易于加氫，Cβ在較高溫度下才能加氫，活性約為Cα的1/100[119]；溫度在600 K以上，Cα可以緩慢轉變為Cβ，Cβ在高溫下轉變為石墨碳。碳須由吸附碳原子在金屬表面進行擴散，并在金屬和載體界面處成核并生長而成[120]。碳須不占據金屬表面，對催化活性沒有太大影響。但是，由于具有很高機械強度，大量碳須生成會使催化劑強度嚴重下降，甚至粉化。因此，從催化劑結構和反應器出發，降低催化劑積炭和燒結仍然是甲烷化反應研究的前沿領域。

基于以上認識，從甲烷化反應過程強化擴散、傳熱角度認識甲烷化反應和降低催化劑積炭和燒結速率引起研究者的關注[121-122]。流化床反應器具有高效的氣固傳質傳熱效率，反應床層內溫度和催化劑顆粒均勻分布等優點，有利于實現對甲烷化反應溫度的控制，抑制床層溫度過熱和防止燒結。研究表明，流化床甲烷化反應可以分為富CO區和貧CO區，高流化氣速有利于強化傳熱，避免出現局部熱點，但高流化氣速也會帶來氣泡快速的穿越催化劑床層，降低反應轉化率[123-124]。同時，催化劑顆粒在流化床中循環流動使得流化床成為積炭的緩沖器，能夠有效防止催化劑積炭，使得流化床甲烷化重新引起重視[45,105,121]。許光文課題組[125-128]研究表明，流化床具有比固定床高的CO轉化率和CH4選擇性，并進一步證實了流化床的強化傳熱效果。

早期的流化床甲烷化工藝研究中發現催化劑顆粒的磨損嚴重[39]，但對流化床甲烷化催化劑的流化行為及催化劑顆粒的流化質量對甲烷化反應的影響很少有文獻報道。近年來，Kai等[129-131]研究表明，甲烷化減分子反應造成催化劑流化質量降低，甚至失流。在其他反應中也發現了減分子反應對流化床反應和反應器放大的不利影響[132-133]。而且，催化劑的磨損使得催化劑顆粒變細，也會導致催化劑的黏結失流，造成CO轉化率和甲烷選擇性降低。Li等[134]也通過添加B類顆粒，改善了催化劑的流化質量，提高了CO轉化率和甲烷選擇性。納米催化劑顆粒具有比普通負載催化劑更高的甲烷化活性，但由于其強的黏結性，極易團聚而導致失流[135-136]，通過外加磁場[137]和預燒結造粒[138]，顯著提高了納米催化劑的流化質量，抑制催化劑燒結和積炭。宗保寧等[139-143]利用磁場強化受傳熱和傳質限制的反應過程，如己內酰胺加氫精制，顯示出良好的工業應用前景。

以往的研究中，忽略了催化劑與反應器的匹配性及甲烷化反應的強放熱和減分子反應特性，是導致流化床甲烷化失敗的一個重要因素。通過顆粒及反應器結構設計，強化傳遞和反應的研究成為新的研究方向[144-156]。微反應器（微通道）具有狹窄的通道、大的比表面積和體積比，大大強化了傳熱和傳質速率，明顯優于傳統的反應器，特別是在甲烷化反應中起到了獨特的作用[144-148]。程易等[121]考慮到選擇適于流化床的甲烷化催化劑顆粒，以易于流化的耐磨損的-Al2O3為載體，通過浸漬法制備了鎳基催化劑。從與流化床反應器匹配的催化劑結構設計源頭出發，采用非常規制備技術手段（如超重力）[153-154]制備具有耐磨損、易流化、低密度的高活性甲烷化催化劑，可能是流化床甲烷化發展的一個重要途徑。

4 結論和展望

甲烷化反應過程的主要問題是“燒結”和“積炭”。現有固定床甲烷化工藝以犧牲生產能力和耗費能量來減少催化劑的積炭和燒結。這為流化床甲烷化反應器及配套催化劑設計帶來了機遇和挑戰。

基于甲烷化反應特點和對甲烷化反應機理的認識，從與流化床反應器-催化劑結構的匹配角度，制備具有耐磨損、易流化、低密度的高活性甲烷化催化劑，可能是流化床甲烷化發展方向。

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Process intensification and catalysts particle design for CO methanation

LI Jun，ZHU Qingshan，LI Hongzhong

State Key Laboratory of Multiphase Complex SystemsInstitute of Process EngineeringChinese Academic SciencesBeijingChina

Carbon deposition and sintering of metal particles are the two dominating reasons for deactivation of the methanation catalyst. Based on the strong exothermic reaction accompanied by a large decrease in mole number and methanation mechanism,from the perspective of the matching of catalyst and reactor, this paper summarizes the development of main CO methanation techniques, CO methanation catalysts, reaction mechanism of CO methanation and its process intensifications. Fluidized bed reactors have the advantages in preventing the carbon deposition and sintering of Ni catalysts. Thus, the design of wear-resistant, easy fluidized and low density catalyst structure particles that applicable to fluidized bed reactors should be a feasible way and the new direction for the development of methanation techniquesfluidized bed reactors.

methanation; fluidized bed reactor; strong exothermic; molecular reduction; Ni catalyst; carbon deposition

2015-05-29.

Prof. ZHU Qingshan, qszhu@ipe.ac.cn

10.11949/j.issn.0438-1157.20150748

TQ 032.4

A

0438—1157（2015）08—2773—11

朱慶山。

李軍（1979—），男，博士，副研究員。

國家自然科學基金項目（91334108）；國家重大科學儀器設備開發專項項目（2011YQ12003908）。

2015-05-29收到初稿，2015-06-10收到修改稿。

supported by the National Natural Science Foundation of China (91334108) and the National Special Project for Development of Major Scientific Equipment (2011YQ12003908).